A/C Request A Circuit Range/Performance
The A/C request input A is electrically intact, but its value does not match the system context — for example asserted while the HVAC controller reports off, toggling rapidly, or sustained while compressor pressures cannot support it. The ECM disables A/C clutch engagement until the input becomes plausible.
Affected components
- Ac request input a
- Hvac module
Common causes
- High likelihood: HVAC module sending inconsistent request
- Low likelihood: Sensor element aged beyond calibration window
- Low likelihood: Sensor mounting loose - signal damping
Diagnostic notes
- The malfunction indicator lamp may illuminate
Related codes
Sources
Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.